WO2004/011537 describes the formation of solid, porous beads comprising a three-dimensional, open-cell lattice of a water-soluble polymeric material with an average bead diameter in the range 0.2-5 mm. These beads are typically “emulsion-templated” materials formed by removal (by drying) of the water and oil from a continuous aqueous phase, in which the water-soluble polymeric material is dissolved, and a disperse oil phase respectively from a high internal phase emulsion. Such removal leaves a “skeletal” form of the emulsion behind “imprinted” into the water-soluble polymeric material. The beads dissolve rapidly in water and have the remarkable property that water-insoluble components incorporated into the emulsion (typically by their dissolution in the disperse oil phase) prior to drying can be dispersed in water on dissolution of the beads.
There are many instances where it would be desirable to provide water-insoluble materials in an aqueous environment either for direct use or for incorporation into a further product/process for onward use. Such water-insoluble materials include pharmaceuticals, nutraceuticals, animal health products, agrochemicals, biocidal compounds, food additives (including flavourings), polymers, proteins, peptides, cosmetic ingredients, coatings, inks/dyes/colourants, laundry or household cleaning and care products.
Similarly, there are instances where it would be desirable to provide water-soluble materials in a non-aqueous environment, again either for direct use or for incorporation into a further product/process for onward use. Such water-soluble materials include pharmaceuticals, nutraceuticals, animal health products, agrochemicals, biocidal compounds, food additives (including flavourings), polymers, proteins, peptides, cosmetic ingredients, coatings, inks/dyes/colourants, laundry or household cleaning and care products.
Throughout the specification, by a “water-soluble material” and like terms, we mean a material that forms a homogeneous solution in water. In the context of the present invention, “water-soluble” means that the solubility of the material in question in water at ambient temperature and pressure is at least 10 g/L. The term “water-soluble” includes the formation of structured aqueous phases as well as true ionic solution of molecularly mono-disperse species.
Conversely, by a “water-insoluble material” and like terms, we mean a material that forms a homogeneous solution in a non-aqueous medium, e.g. an organic solvent or oil. In the context of the present invention, “water-insoluble” means that the solubility of the material in question in water at ambient temperature and pressure is less than 10 g/L.
For the avoidance of any doubt, in the present application the term “ambient temperature” means 25° C. whilst “ambient pressure” means 1 atmosphere (101.325 kPa) of pressure.
As an example to illustrate the problem, prochloraz and λ-cyhalothrin are both active biocide materials (a foliar fungicide and a pyrethroid insecticide respectively) which are water-insoluble (0.039 g/L and 0.005 g/L at 20° C. respectively). It would be useful to be able to deliver both of these materials from an aqueous system/environment.
With this problem in mind, the inventors have previously devised what are known herein as “carrier liquids”. These are compositions which are liquid at ambient temperature and pressure and contain a liquid-insoluble material (hereinafter referred to as a “dopant material”) in a disperse, preferably nano-disperse, form. By “liquid-insoluble” it is meant that the dopant material is not normally soluble in the liquid, i.e. a solid body of the dopant material introduced into the liquid (in an amount of 1 mg/ml) will remain as such (i.e. solid) without dissolving. By “nano-disperse form” and like terms it is meant that the material in question is present in the carrier liquid as discrete nanoparticles of z-average diameter less than 1000 nm.
The present inventors previously discovered (as described and claimed in WO2006/079410A1) that such carrier liquids could be prepared by utilising a method comprising preparing an emulsion from a) an aqueous phase, b) a second liquid phase, which is volatile and immiscible with the aqueous phase, c) a carrier material, which is soluble in the continuous phase of the emulsion and liquid at ambient temperature, and d) a dopant material, which is soluble in the disperse phase of the emulsion, and subsequently cooling the emulsion until both the continuous phase and the carrier material become solid (i.e. they freeze), followed by removal of water and the volatile second phase from the cooled emulsion in vapour form to obtain a liquid product (at ambient temperature) with the dopant material dispersed therein.
Although this method is successful, there is however a need to improve upon it by simplifying the formation of the emulsion as the intermediate phase to be dried. The present inventors have now determined that an improvement to the known “emulsion method” can be obtained if a single solvent or a mixture of miscible solvents which comprise a single phase solution are used instead of mixtures of immiscible aqueous/non-aqueous solvents that would be used to form an emulsion.